Effects Of Fucoidan On Angiogenesis Indecued By Human Multiple Myeloma Cells

Objective: In multiple myeloma patients, microvessel density is high and it is hypoxia in their bone marrow which exacerbation angiogenesis, all that is related to progression and prognosis of patients. There are researchs have founded that Fucoidan inhibited the growth of MM cells, but no one knows the effects of Fucoidan on angiogenesis induced by human myeloma cells. Therefore, we intend to investigate the effects of Fucoidan on angiogenesis induced by multiple myeloma cells and its related mechanisms.Methods: The human multiple myeloma cells were treated with Fucoidan at different concentrations with normoxic and hypoxic conditions, then the conditioned medium(CM) was collected and the levels of VEGF in it were tested by ELISA. The tube formation assay and migration test on HUVECs were used to examine the effect of Fucoidan on angiogenesis induced by human myeloma cells. After treated with Fucoidan with normoxic and hypoxic conditions, the protein levels of HIF-1α, VEGF, p-AKT, p-ERK1/2 were detected by Western blotting. Also, multiple myeloma xenograft mouse model was set up, we observed their growth after intraperitoneal injection of Fucoidan. When the mice were sacrificed with 3 weeks of treatments, the tumors sections were stained with HE and TUNEL, then immunohistochemical staining of CD34 to assess MVD was performed.Results: The VEGF concentration was significantly decreased with with the increasing concentration of fucoidan, no matter of normoxic or hypoxic condition. The number and area of the capillary-like structures decreased while the concentration of fucoidan increased, that at 100 μg/mL were less than that in the control(P<0.05). HUVECs were inhibited to migrate pretreated with the high dose-Fucoidan, similar results were obtained hypoxic condition. The protein levels of HIF-1α, VEGF, p-AKT, p-ERK1/2 from MM cells treated with fucoidan under normoxic condition were significantly lower than that in control group, but p-ERK1/2 changed little when MM cells treated with fucoidan under hypoxic condition. As for the effects of Fucoidan in mice, the average tumor volume and weight in the Fucoidan treated group III(50 mg/kg body weight) was significantly smaller and lighter than that in the controls, the apoptotic cells were increased significantly in treated mice. Immunohistochemistry for CD34+ on tumor sections showed a significant reduction in the number of CD34+ vessels within group III(50 mg/kg body weight).Conclusion: Fucoidan inhibits the secretion of VEGF in multiple myeloma cells no matter of normoxic or hypoxic condition, at the same time, it reduces angiogenesis induced by multiple myeloma cells in vitro. It may be related to inhibiting the expression of HIF-1α, VEGF, p-AKT and p-ERK1/2(not under hypoxic condition). The study on mouse model tells that neovascularization in tumor was inhibited by Fucoidan even in vivo.